Tender Springs (also known as helper springs)

[thehueypilot]

This is a new concept for me on coil-over springs as it is a NASCAR/road racing thing? I am going to try them on my 89 Mustang Pro-Touring car. I am not sure about the lb/in requirement. Besides taking up the slack on a 10" spring do I size it for a soft ride (150 lb/in tender spring) and good handling (300 lb/in 10" long coil spring) or do I have this backwards? I notice some springs are 50 lb/in which are only good for removing the slack in a shorter spring? This looks like a good alternative to a one piece progressive rate spring? The link shows the springs on the right side picture (two separate springs) except mine would be stacked opposite for more strut to rim clearance.

http://eibach.com/america/en/performance-suspension/coilover-suspension-systems

Tim

 

[2012-Boss]

The only thing a tender spring is used for is to keep the main spring fully seated when the shock or strut is fully extended. Examples include jacking the car up or hitting curbing hard enough that a wheel is no longer in contact with the pavement. Many of the springs used on aftermarket coil overs are not long enough to remain seated.

The tender has no impact on overall spring rate. They are usually soft enough that you can move the spring(s) up and down by hand when there is no load on the strut / shock.